1. Field of the Invention
The present invention relates to a flow board of a fuel cell and a manufacturing method thereof, and more particularly, to a flow board with high methanol resistance and high mechanical strength, superior fuel flow efficiency, and low cost.
2. Description of the Prior Art
As is well known, direct methanol fuel cells (DMFCs) are power packages that use diluted methanol liquid as fuel, and change chemical energy to electric power electro-chemically. Compared with previous power generating methods, DMFCs have the advantages of low pollution, low noise, high energy density, and higher energy exchange rates. DMFCs are a clean energy resource, and can be applied in family power generated systems, uninterruptible power systems, electric products, transport, military equipment, and the space industry.
The operating principle of DMFCs is oxidizing the methanol liquid in the anode catalyst layer to generate hydrogen ions (H+), electrons (e−), and carbon dioxide (CO2). The hydrogen ions are input to the cathode by an electrolyte. At the same time, oxygen is supplied to the cathode, and the hydrogen ions and electrons in the cathode catalyst layer undergo a reduction reaction to generate water. In general, fuel cells are made from many basic units. Each basic unit provides low voltage so many basic units must connect in series to output a required operating voltage.
The DMFC module usually includes a current collector and a flow board, which both play important roles. The current collector collects the electrons generated from the electron-chemical reaction, and the flow board manages and controls the distribution of the fuel. In the past, the flow board design has focused on enabling fuel to pass smoothly through the fuel channel into the membrane electrode assembly (MEA).
The prior flow boards use graphite or glass fiberboard such as FR4, FR5 as the materials of the body substrates. The flow boards are conventionally made by using a computer numerical control (CNC) mill lathe. The shortcomings of CNC mill lathe include low yield, and high cost. The prior body substrates, which are made of graphite, FR4, or FR5, have poor mechanical properties, and occupy too much space. The above reasons are disadvantageous for the yield and popularization of the fuel cell.
In conclusion, a well designed flow board does not only depend on choosing a material that is resistive to corrosion caused by gaseous/liquid fuel and/or the chemical reactant, but also requires choosing a material that has superior mechanical properties, low cost, and fast mass production. There is a need to improve both the materials and the manufacturing methods utilized in conventional flow boards.